Asexual propagation for plants has been shown for some species to yield large numbers of genetically identical embryos, each having the capacity to develop into a normal plant. Such embryos must usually be further cultured under laboratory conditions until they reach an autotrophic “seedling” state characterized by an ability to produce its own food via photosynthesis, resist desiccation, produce roots able to penetrate soil, and fend off soil microorganisms. Some researches have experimented with the production of artificial seeds, known as manufactured seeds, in which individual plant somatic or zygotic embryos are encapsulated in a seed coat. Examples of such manufactured seeds are disclosed in U.S. Pat. No. 5,701,699, issued to Carlson et al., the disclosure of which is hereby expressly incorporated by reference.
Typical manufactured seeds include a seed shell, synthetic gametophyte, and a plant embryo. A manufactured seed that does not include the plant embryo is known in the art as a “seed blank.” The seed blank typically is a cylindrical capsule having a closed end and an open end. Synthetic gametophyte is placed within the seed shell to substantially fill the interior of the seed shell. A longitudinally extending hard porous insert, commonly known as a cotyledon restraint, may be centrally located within the synthetic gametophyte. The cotyledon restraint includes a centrally located cavity extending partially through its length. The cavity is sized to receive a plant embryo therein.
The well-known plant embryo includes a radicle end and a cotyledon end. The plant embryo is deposited within the cavity of the cotyledon restraint, cotyledon end first. The embryo is sealed within the seed blank by at least one end seal. There is a weakened spot in the end seal to allow the radical end of the embryo to penetrate the end seal. Thus, currently available manufactured seeds include a separate cotyledon restraint and an entirely separate end seal to seal the synthetic gametophyte within the seed shell.
Although such manufactured seeds are effective, they are not without their problems. As a non-limiting example, the manufacturing process of such seeds, while not expensive, is increased in cost by the need to design and manufacture each component of the manufactured seed, as well as the cost of assembling multiple parts. Additionally, because the cotyledon restraint is a separate subcomponent of the manufactured seed, centering the opening of the cotyledon restraint relative to the sidewalls of the seed shell requires additional manipulation either during assembly or during insertion of the embryo within the cotyledon restraint. Manufacturing artificial seeds can, therefore, be time-intensive. As a result, mass production of manufactured seeds could be made more efficient by reducing the number of parts necessary to manufacture.
Thus, there exists a need for an apparatus that combines both the end seal and the cotyledon restraint into a single apparatus, thereby eliminating the need for both a cotyledon restraint and an end seal.